The factory requires a GL5 rating. If you want to stay in GM land the part number for their lube is 88862475. We use AMSOIL Severe Gear 75W-90 as it has some pretty hefty extreme pressure additives and I've had nothing but positive feedback about smoth shifts and better cold temp operation.

Just drained and filled the tranny and the rear differential. Used mobile 1 ls for both. I had a friend who owns a shop put it on his lift to do. Way easy with the lift. I also added the slip additive to the rear diff. The fluid that came outa there after only 10000 miles was sick. Tons of metal on the magnet and in the oil. The transmission oil looked ok but still was glad to change out. Overall the fluids cost me $35 and my buddy $20 for labor. WAY better than the stealership. Going to record the service in my manual and take the rest of the day off !

Just drained and filled the tranny and the rear differential. Used mobile 1 ls for both. I had a friend who owns a shop put it on his lift to do. Way easy with the lift. I also added the slip additive to the rear diff. The fluid that came outa there after only 10000 miles was sick. Tons of metal on the magnet and in the oil. The transmission oil looked ok but still was glad to change out. Overall the fluids cost me $35 and my buddy $20 for labor. WAY better than the stealership. Going to record the service in my manual and take the rest of the day off !

Im assuming there isn't a slip additive in the Mobil 1 oil for the Diff?... Im about to change mine (2010 v6 M6) and was just curious...If its not in the Mobil 1, what slip additive did you use?

No, I looked and didn't find anything. I used the GM slip additive. The part number is in your manual in the fluids section. I read a lot where people said if you use the mobile 1 ls, you don't need the additive, but I wanted to follow the directions.

No, I looked and didn't find anything. I used the GM slip additive. The part number is in your manual in the fluids section. I read a lot where people said if you use the mobile 1 ls, you don't need the additive, but I wanted to follow the directions.

Oh okay, thanks. Now idk whether to get the mobil 1 use what came in the car?

On a sidenote i use Mobil 1 for the engine, guess i just want to use the same brand for everything...

Just drained and filled the tranny and the rear differential. Used mobile 1 ls for both. I had a friend who owns a shop put it on his lift to do. Way easy with the lift. I also added the slip additive to the rear diff. The fluid that came outa there after only 10000 miles was sick. Tons of metal on the magnet and in the oil. The transmission oil looked ok but still was glad to change out. Overall the fluids cost me $35 and my buddy $20 for labor. WAY better than the stealership. Going to record the service in my manual and take the rest of the day off !

I used syncromesh for my trans, it saved it on a track day where my temps in the trans rose to 300 degrees. Not enough fluid in the Aisen Trans, may look at adding a cooler and additional tank down the line to keep it cool.